>> reporter: to re-create the disaster, physicist steve wolf and the team test each theory, one at a time. lightning, a bomb, a spark. the question is, was the hindenberg brought down by mother nature, sabotage, or something else? >> in our lab testing, most of those theories really didn't pan out. but one of them does. >> reporter: after 75 years, the team will make the public wait just a bit longer for the answer. releasing their findings on sunday. jon schriffen, abc news, new york. >> should be fascinating what answer they come up with. obviously, it's best known for those fiery images. but in its heyday, that was the fastest and most comfortable way to get across the atlantic. so it was a milestone at the time. of course, we remember how it ended, just like the "titanic." we remember the tragedy, not the accomplishment. >> that was the first trip from europe to north america of the 1937 and they didn't have a full airship, only 36 passengers.